Facile Enzymatic Synthesis of Ketoses and Chemoenzymatic Reporter Strategy for Probing Complex Glycans

Of all possible ketoses, only D-fructose occur large scale in nature. Therefore, all the ketoses with the exception of D-fructose are defined as “rare ketose”. Despite their lower accessibility, rare ketoses offer an enormous potential for applications in pharmaceutical, medicine, functional food and synthetic chemistry. However, studies of rare ketoses have been hampered by the lack of efficient preparation methods. Here, a convenient and efficient platform for the facile synthesis of rare ketoses is described. The introduced two-step strategies are based on a “phosphorylation/de-phosphorylation” cascade reaction. Rare ketoses were prepared from readily available starting materials as their ketose-1-phosphate forms in step 1 by one-pot multienzyme reactions, followed by the hydrolysis of the phosphate groups in acidic conditions to produce desired ketoses in step 2. By this strategy, 14 rare ketoses were obtained from readily available starting materials with high yield, high purity, and without having to undergo tedious isomer separation step. Sialic acids are typically linked a2-3 or a2-6 to the galactose that located at the nonreducing terminal end of glycans, playing important but distinct roles in a variety of biological and pathological processes. However, details about their respective roles are still largely unknown due to the lack of an effective analytical technique. Lectin and antibody binding have been the primary method to analyze glycans, but lectins and antibodies often suffer from weak binding affinity, limited specificity, and cross-reactivity. To address this issue, we develop a chmoenzymatic reporter strategy for rapid and sensitive detection of N-acetylneuraminic acid-a(2-3)-Galactose (Neu5Aca(2-3)Gal) glycans on cell surface

Production of Glycopeptide Derivatives for Exploring Substrate Specificity of Human OGA Toward Sugar Moiety.

O-GlcNAcase (OGA) is the only enzyme responsible for removing N-acetyl glucosamine (GlcNAc) attached to serine and threonine residues on proteins. This enzyme plays a key role in O-GlcNAc metabolism. However, the structural features of the sugar moiety recognized by human OGA (hOGA) remain unclear. In this study, a set of glycopeptides with modifications on the GlcNAc residue, were prepared in a recombinant full-length human OGT-catalyzed reaction, using chemoenzymatically synthesized UDP-GlcNAc derivatives. The resulting glycopeptides were used to evaluate the substrate specificity of hOGA toward the sugar moiety. This study will provide insights into the exploration of probes for O-GlcNAc modification, as well as a better understanding of the roles of O-GlcNAc in cellular physiology

Production of Glycopeptide Derivatives for Exploring Substrate Specificity of Human OGA Toward Sugar Moiety

O-GlcNAcase (OGA) is the only enzyme responsible for removing N-acetyl glucosamine (GlcNAc) attached to serine and threonine residues on proteins. This enzyme plays a key role in O-GlcNAc metabolism. However, the structural features of the sugar moiety recognized by human OGA (hOGA) remain unclear. In this study, a set of glycopeptides with modifications on the GlcNAc residue, were prepared in a recombinant full-length human OGT-catalyzed reaction, using chemoenzymatically synthesized UDP-GlcNAc derivatives. The resulting glycopeptides were used to evaluate the substrate specificity of hOGA toward the sugar moiety. This study will provide insights into the exploration of probes for O-GlcNAc modification, as well as a better understanding of the roles of O-GlcNAc in cellular physiology

Index modulation for 5G wireless communications

This book presents a thorough examination of index modulation, an emerging 5G modulation technique. It includes representative transmitter and receiver design, optimization, and performance analysis of index modulation in various domains. First, the basic spatial modulation system for the spatial domain is introduced. Then, the development of a generalized pre-coding aided quadrature spatial modulation system as well as a virtual spatial modulation system are presented. For the space-time domain, a range of differential spatial modulation systems are examined, along with the pre-coding design. Both basic and enhanced index modulated OFDM systems for the frequency domain are discussed, focusing on the verification of their strong capabilities in inter-carrier interference mitigation. Finally, key open problems are highlighted and future research directions are considered. Designed for researchers and professionals, this book is essential for anyone working in communications networking, 5G, and system design. Advanced-level students of engineering and computer science interested in efficiency techniques will also find the content valuable

Index modulated OFDM with interleaved grouping for V2X communications

The rapid penetration of intelligent transportation systems (ITS) into the conventional transportation infrastructure urgently calls for high spectral efficiency high reliability communication technology for vehicle-to-vehicle and vehicle-to-infrastructure (V2X) applications. Since orthogonal frequency division multiplexing (OFDM) is widely considered as a promising candidate for such applications, in this paper we propose a novel variation of OFDM for improved spectral efficiency as well as enhanced reliability in V2X channels with correlated frequency-selective fading and inevitable Doppler effects. Our proposed scheme is built upon a recently emerging technique termed as index modulated (IM-) OFDM. However, different from the existing localized subcarrier grouping, we propose interleaved subcarrier grouping. We then carry out analytical and simulated comparisons to demonstrate the merits of this new scheme in terms of both the bit error rate (BER) performance and the maximum achievable rate (MAR) of the overall system, in V2X channels.EICPCI-S(ISTP)[email protected]; [email protected]; [email protected]; [email protected]

Two-path transmission framework for ICI reduction in OFDM systems

Two-path transmission schemes have attracted much attention due to its effectiveness in suppressing intercarrier interference (ICI) in orthogonal frequency-division multiplexing (OFDM) systems. This paper proposes a general implementation framework for the existing two-path transmission schemes, which not only reveals the underlying relationship between the existing two-path transmission schemes and the mirror-subcarrier-mapping based ICI self-cancellation technique but also owns the advantage of backward compatibility with normal OFDM systems. Moreover, using the proposed framework, new two-path transmission schemes can be easily developed. With insights provided by this framework, the carrier-to-interference power ratio (CIR) and the bit error probability (BEP) achieved by the existing two-path transmission schemes are further analytically investigated. Monte Carlo simulations validate the analysis. ? 2013 IEEE.EI